Method and system for controlling irrigation using computed evapotranspiration values

ABSTRACT

A system for providing irrigation control is provided. The system includes a number of non-local data sources for providing data, a processor and an irrigation system. The processor is configured to receive data from one or more of the non-local data sources and calculate an evapotranspiration (ET) value for an irrigation area that is non-local with respect to the non-local data sources. The irrigation system is located in the irrigation area and configured to receive the ET value from the processor and provide appropriate irrigation control for the irrigation area using the ET value.

CROSS-REFERENCES TO RELATED APPLICATION(S)

The present application claims the benefit of priority under 35 U.S.C.§119 from (1) U.S. Provisional Patent Application Ser. No. 60/515,905,entitled “METHOD FOR PROVIDING OFFSET TO COMPUTED EVAPOTRANSPIRATIONVALUES”, filed on Oct. 29, 2003, (2) U.S. Provisional Patent ApplicationSer. No. 60/515,932, entitled “METHOD FOR CONTROLLING IRRIGATION USINGCOMPUTED EVAPOTRANSPIRATION VALUES”, filed on Oct. 29, 2003, and (3)U.S. Provisional Patent Application Ser. No. 60/515,628, entitled“METHOD FOR CONTROLLING AN IRRIGATION SCHEDULING ENGINE USING COMPUTEDEVAPOTRANSPIRATION VALUES”, filed on Oct. 29, 2003, the disclosures ofwhich are hereby incorporated by reference in their entirety for allpurposes.

BACKGROUND OF THE INVENTION

The present invention generally relates to irrigation control and, morespecifically, to methods and systems for controlling irrigation usingcomputed evapotranspiration (ET) values in a remote manner.

Typically, irrigation control information is manually input by an userto an irrigation system in order to allow the irrigation system toprovide an appropriate amount of irrigation. Such irrigation controlinformation is generally based on measurements obtained by the user fromother equipment and/or data collected by a weather station. Theirrigation system, in turn, provides an appropriate amount of irrigationbased on the input information.

The foregoing irrigation arrangement has a number of shortcomings. Forexample, the user has to first obtain the requisite irrigation controlinformation and then manually input such information into the irrigationsystem. Furthermore, such information does not necessarily accuratelyreflect the local weather conditions that are applicable to the areascovered by the irrigation system. This is because the irrigation controlinformation may be generated based on data collected by a distant ornon-local weather station that is located some distance away from theareas covered by the irrigation system. The weather station may belocated in an area where the weather conditions vary quite significantlyfrom those of the areas covered by the irrigation system. As a result,the irrigation control information (which is based on data collectedfrom the distant weather station) may cause the irrigation system toprovide irrigation that is substantially different from what is requiredfor the areas covered by the irrigation system.

Hence, it would be desirable to provide a system that is capable ofproviding accurate irrigation control information using non-local datasources.

SUMMARY OF THE INVENTION

In one embodiment, a system for providing irrigation control isprovided. The system includes a number of non-local data sources forproviding data, a processor configured to receive data from one or moreof the plurality of non-local data sources and calculate anevapotranspiration (ET) value for an irrigation area that is non-localwith respect to the non-local data sources, and an irrigation systemconfigured to receive the ET value from the processor and provideappropriate irrigation control for the irrigation area using the ETvalue.

In another embodiment, a system for providing irrigation control isprovided which includes a number of non-local data sources for providingdata, a processor configured to receive data from one or more of thenon-local data sources and calculate one or more components to be usedfor computing an evapotranspiration (ET) value for an irrigation areathat is non-local with respect to the non-local data sources, and anirrigation system configured to receive the one or more components fromthe processor; the irrigation system is further configured to use theone or more components received from the processor to compute the ETvalue and provide appropriate irrigation control for the irrigation areabased on the computed ET value.

In yet another embodiment, a system for providing irrigation control isprovided which includes a number of non-local data sources for providingdata, a processor configured to receive data from one or more of thenon-local data sources and calculate weather parameters using a modelingapplication, the processor further configured to use the weatherparameters to compute an evapotranspiration (ET) value for an area thatis non-local with respect to the non-local data sources, and anirrigation system located in the area and configured to receive the ETvalue from the processor and provide appropriate irrigation control forthe area using the ET value.

In a further embodiment, a system for providing irrigation controlincludes a number of non-local data sources for providing data, aprocessor configured to receive data from one or more of the non-localdata sources and calculate an evapotranspiration (ET) value for anirrigation area that is non-local with respect to the non-local datasources, the processor further configured to decompose the ET value intoone or more components, and an irrigation system configured to receivethe one or more components from the processor, the irrigation systemfurther configured to use the one or more components received from theprocessor to derive the ET value and provide appropriate irrigationcontrol for the irrigation area based on the ET value computed by theprocessor.

In one aspect of the present invention, a method for providingirrigation control is provided. The method comprises: receiving datafrom one or more non-local data sources, calculating anevapotranspiration (ET) value based on the data received from the one ormore non-local data sources, wherein the ET value is for an area that isnon-local with respect to the non-local data sources, and providingappropriate irrigation control for the area using the ET value.

In another aspect of the present invention, a method for providingirrigation control includes: receiving data from one or more non-localdata sources, calculating one or more components to be used forcomputing an evapotranspiration (ET) value based on the data receivedfrom the one or more non-local data sources, wherein the ET value is foran area that is non-local with respect to the non-local data sources,and transmitting the one or more components to an irrigation systemlocated in the area.

In a further aspect of the present invention, a method for providingirrigation control includes: receiving data from one or more non-localdata sources, calculating weather parameters using a modelingapplication, using the weather parameters to compute anevapotranspiration (ET) value based on the data received from the one ormore non-local data sources, wherein the ET value is for an area that isnon-local with respect to the non-local data sources, and transmittingthe ET value to an irrigation system located in the area.

Reference to the remaining portions of the specification, including thedrawings and claims, will realize other features and advantages of thepresent invention. Further features and advantages of the presentinvention, as well as the structure and operation of various embodimentsof the present invention, are described in detail below with respect toaccompanying drawings, like reference numbers indicate identical orfunctionally similar elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects, advantages and novel features of the present invention willbecome apparent from the following description of the inventionpresented in conjunction with the accompanying drawings:

FIG. 1 is a simplified schematic block diagram illustrating oneembodiment of the present invention; and

FIG. 2 is a simplified schematic block diagram illustrating oneembodiment of an irrigation system according to the present invention.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The present invention in the form of one or more embodiments will now bedescribed. As shown in FIG. 1, one embodiment of the present inventionis a system 100 that includes a number of non-local data sources 102a-c, a processor 104 and an irrigation system 106. The processor 104 isconfigured to receive data from one or more of the non-local datasources 102 a-c, use such data to compute an ET value and then transferthe computed ET value to the irrigation system 106. The irrigationsystem 106 is configured to receive the computed ET value from theprocessor 104 and provide irrigation or perform other irrigationfunctions accordingly.

Each data source 102 provides information that can be utilized togenerate irrigation control information including, for example, an ETvalue. The ET value is calculated based on a number of parametersincluding, for example, relative humidity, soil temperature, airtemperature, wind speed and solar radiation. The number of parametersmay vary depending on the methodology that is used to calculate the ETvalue. The data sources 102 a-c collectively provide information onthese parameters. Each data source 102 may provide informationcorresponding to one or more parameters. The information is then used tocompute the ET value, as will be further described below. Data from thenon-local data sources 102 a-c is used because the area in which theirrigation system 106 is located does not have sufficient measuringapparatus or resources to obtain local information that is needed todetermine the ET value in that area.

The data sources 102 a-c are non-local in the sense that they are notlocated in the same general area as the irrigation system 106. Forexample, one data source is the National Weather Service which providesgeneral weather information across the United States; other data sourcesinclude databases or data feeds from various universities and governmentagencies. It should be understood that the meaning of the term“non-local” is not strictly defined by physical distance; “non-local”may also refer to an area that is subject to generally different weatherconditions. For example, two areas may be physically close to oneanother; however, they may be non-local with respect to each otherbecause they have generally different weather conditions attributed todifferent geographical topologies and different topographies. Asmentioned before, the data sources 102 a-c collectively provide datathat relate to the various parameters that are used to compute the ETvalue for the area(s) covered by the irrigation system 106. For example,data collected from the data sources 102 a-c include surfaceobservations, upper air observations, sea surface temperatures andcurrent global initialization 4D (4-dimensional) grids, etc.

Data from the data sources 102 a-c are transmitted to the processor 104.It should be noted that data from the data sources 102 a-c can betransmitted to the processor 104 in a number of ways including, forexample, via a computer network such as the Internet. Based on thedisclosure and teachings provided herein, a person of ordinary skill inthe art will know of other ways and/or methods to transmit the data fromthe data sources 102 a-c to the processor 104 in accordance with thepresent invention.

The processor 104, in turn, processes the data to calculate the desiredET value for each particular area covered by the irrigation system 106.First, the processor 104 calculates the requisite weather parameters in4D space.

The weather parameters in 4D space are calculated as follows. Thegridded terrain elevation, vegetation and land use are horizontallyinterpolated onto each mesoscale domain. Input fields such as soiltypes, vegetation fraction, and deep soil temperature, are populatedfrom historical data.

Then, the 4D gridded meteorological analyses on pressure levels areinput and those analyses are interpolated from global grids to eachmesoscale domain. The foregoing steps perform the pressure-level andsurface analyses. Two-dimensional interpolation is performed on theselevels to ensure a completely populated grid.

Next, the global initialization on each mesoscale grid is adjusted byincorporating observation data from the data sources 102 a-c. Differenttypes of observation data are used including, for example, traditionaldirect observations of temperature, humidity, wind from surface andupper air data as well as remote sensed data, such as, radar andsatellite imagery. The three-dimensional and four-dimensionalvariational techniques both integrate and perform quality control on thedata, eliminating questionable data to improve the global initializationgrids.

The initial boundary conditions are then calculated and formatted forinput to a numerical weather model. It will be appreciated that a numberof different numerical weather models can be used depending on eachparticular application. Based on the disclosure and teachings providedherein, a person of ordinary skill in the art will know how to selectthe appropriate numerical weather model in accordance with the presentinvention. For example, one process converts pressure level data to an“S” coordinate system under bounded conditions in 4D space (x, y, z andtime). The integrated mean divergence or noise conditions that theinitial analyses may contain are then removed to create a stable basestate for the numerical weather model.

Using the numerical weather model, and the appropriate physics options,the requisite weather parameters in 4D space are then calculated. Thisis a fully bounded 4D grid in both space and time with known startingand ending conditions.

Calculation of the weather parameters can be performed by the processor104 using a number of modeling applications (not shown) that arepublicly available. These modeling applications can be modified toperform the functions as described above. One such modeling applicationis known as the PSU/NCAR mesoscale model (known as MM5). The MM5 is alimited-area, nonhydrostatic, terrain-following sigma-coordinate modeldesigned to simulate or predict mesoscale atmospheric circulation.Another such modeling application is the WRF (Weather Research andForecasting) model created by UCAR (University Corporation forAtmospheric Research). Based on the disclosure and teachings providedherein, a person of ordinary skill in the art will know how to selectand modify the various available modeling applications for use inaccordance with the present invention.

The calculated weather parameters outputted from the numerical weathermodel are then used to calculate the ET value for a target location in2D space. Corresponding weather parameters needed for calculating the ETvalue for the target location are extracted at specific x, y, z & timelocations.

The ET value at the target location is then calculated and a 2D griddedsurface for the 24 hour period is created. It should be understood thatthe ET value may be calculated based on one of a number of differentformulas. Based on the disclosure and teachings provided herein, aperson of ordinary skill in the art will appreciate how to select theappropriate formula depending on each particular situation.

Finally, any artifacts, edge effects and anomalies created by mesoscalegrid boundaries conditions and/or errors are eliminated.

The processor 104 then transfers the computed ET value to the irrigationsystem 106. Upon receiving the computed ET value, the irrigation system106 can then provide the proper irrigation or perform other irrigationfunctions in an automated manner.

The processor 104 is typically located at some distance away from theirrigation system 106. The transfer of the computed ET value from theprocessor 104 to the irrigation system 106 can be done in a number ofways. For example, the computed ET value can be transmitted to theirrigation system 106 via wired or wireless communications. Based on thedisclosure and teachings provided herein, a person of ordinary skill inthe art will know of other ways and/or methods to transfer the computedET value from the processor 104 to the irrigation system 106.

Furthermore, in one embodiment, the processor 104 first encrypts ormathematically alters the computed ET value before transferring it tothe irrigation system 106. The irrigation system 106 is equipped withthe corresponding decryption algorithm to decrypt or restore thecomputed ET value.

In an alternative embodiment, after the processor 104 derives theweather parameters, such weather parameters are transferred to theirrigation system 106. Using the transferred weather parameters, theirrigation system 106 then computes the appropriate ET value.Optionally, the processor 104 can encrypt the weather parameters beforetransferring them to the irrigation system 106 and the irrigation system106 is equipped with the corresponding decryption algorithm to decryptor restore such data.

In one embodiment, as shown in FIG. 2, the irrigation system 106 furtherincludes a scheduling engine 108. The scheduling engine 108 furtherincludes an irrigation program 110 that is designed to control variouscomponents of the irrigation system 106 to automatically provide properirrigation or perform other irrigation functions. The scheduling engine108 may use the received or derived computed ET value to either createone or more new irrigation programs or, alternatively, alter one or moreexisting irrigation programs.

In an alternative embodiment, after the processor 104 computes the ETvalue as described above, the processor 104 uses the computed ET valueto create or alter an irrigation program 110 suitable for the irrigationsystem 106. The irrigation program 110 is then transferred or uploadedto the irrigation system 106. Subsequently, the scheduling engine 108uses the irrigation program 110 to provide the proper irrigation orperform other irrigation functions.

Alternatively, the processor 104 uses the computed ET value to createinformation that can be used by the scheduling engine 108 to update oralter the irrigation program 110. Such information is then forwarded bythe processor 104 to the scheduling engine 108 so as to allow thescheduling engine 108 to update or alter the irrigation program 110.

In another alternative embodiment, after the irrigation program 110 iscreated or altered, the processor 104 breaks down the irrigation program110 into one or more component values. Such component values are thentransferred from the processor 104 to the scheduling engine 108. Thescheduling engine 108 uses such component values to derive orre-constitute the irrigation program 110. The irrigation program 110 isthen used by the scheduling engine 108 to provide the proper irrigationor perform other irrigation functions. The component values of theirrigation program 110 may be individually transmitted to the schedulingengine 108 at different times.

Optionally, the irrigation program 110 or component values thereof aremathematically altered or encrypted before they are transferred to theirrigation system 106 by the processor 104. The irrigation system 106 isequipped with the corresponding decryption algorithm to decrypt orrestore the irrigation program 110 or component values thereof.

In one embodiment, the irrigation program 110 has a number of discretestates respectively representing various stages of irrigation to beprovided by the irrigation system 106. The processor 104 executes theirrigation program 110 and, upon arriving at a particular discretestate, the processor 104 transfers information relating to thatparticular discrete state to the scheduling engine 108. The schedulingengine 108, in response, provides the proper irrigation or performsother irrigation functions.

Optionally, the information relating to the discrete states can bemathematically altered or encrypted before it is transferred to thescheduling engine 108. The scheduling engine 108 is equipped with thecorresponding decryption algorithm to decrypt or restore suchinformation.

In addition, in some situations, the ET value is computed based onerroneous information. In one embodiment, the processor 104 isconfigured to re-calculate a new, correct ET value using the latest,accurate information. Moreover, using the new ET value and the old ETvalue, the processor 104 is further configured to calculate an offset.The offset is similar to a delta function that represents a correctionto the old ET value. The processor 104 then transfers the offset to theirrigation system 106. The irrigation system 106, in turn, updates theold ET value with the offset and provides the appropriate irrigation orperforms other irrigation functions via, for example, the schedulingengine 108 and/or the irrigation program 110. Since the old ET value istaken into consideration when the offset is calculated, past erroneousirrigation is corrected by the irrigation system 106 when the offset isused by the scheduling engine 108 and/or irrigation program 110 toprovide the proper irrigation.

Optionally, the offset can be mathematically altered or encrypted beforeit is transferred to the irrigation system 106.

In an alternative embodiment described above where the processor 104creates or alters an irrigation program 110 based on the computed ETvalue, the processor 104 can further utilize the offset to create a newirrigation program or alter an existing irrigation program. The new oraltered irrigation program can then be forwarded to the irrigationsystem 106.

In an exemplary implementation, the present invention is implementedusing software in the form of control logic, in either an integrated ora modular manner. The control logic may reside on a computer-readablemedium executable by the processor 104 or a computer. Alternatively,hardware or a combination of software and hardware can also be used toimplement the present invention. Based on the disclosure and teachingsprovided herein, a person of ordinary skill in the art will know ofother ways and/or methods to implement the present invention.

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference for allpurposes in their entirety.

1. A system for providing irrigation control, comprising: a plurality ofnon-local data sources for providing data; a processor configured toreceive data from one or more of the plurality of non-local data sourcesand calculate an evapotranspiration (ET) value for an irrigation areathat is non-local with respect to the plurality of non-local datasources; and an irrigation system configured to receive the ET valuefrom the processor and provide appropriate irrigation control for theirrigation area using the ET value.
 2. The system of claim 1 wherein theprocessor is further configured to use a modeling application tocalculate weather parameters using data received from one or more of theplurality of non-local data sources and further utilize the weatherparameters to generate the ET value.
 3. The system of claim 2 whereinthe modeling application includes a mesoscale model known as MM5.
 4. Thesystem of claim 2 wherein the modeling application includes the WeatherResearch and Forecasting Model.
 5. The system of claim 1 wherein theprocessor is further configured to encrypt the ET value for transmissionto the irrigation system; and wherein the irrigation system is furtherconfigured to decrypt the ET value received from the processor.
 6. Thesystem of claim 1 wherein the irrigation area does not have sufficientmeasuring apparatus to capture local information that is needed tocalculate the ET value for the irrigation area.
 7. A system forproviding irrigation control, comprising: a plurality of non-local datasources for providing data; a processor configured to receive data fromone or more of the plurality of non-local data sources and calculate oneor more components to be used for computing an evapotranspiration (ET)value for an irrigation area that is non-local with respect to theplurality of non-local data sources; and an irrigation system configuredto receive the one or more components from the processor.
 8. The systemof claim 7 wherein the irrigation system is further configured to usethe one or more components received from the processor to compute the ETvalue and provide appropriate irrigation control for the irrigation areabased on the computed ET value.
 9. The system of claim 7 wherein theprocessor is further configured to use a modeling application tocalculate weather parameters using data received from one or more of theplurality of non-local data sources and further utilize the weatherparameters to generate the one or more components.
 10. The system ofclaim 9 wherein the modeling application includes a mesoscale modelknown as MM5.
 11. The system of claim 9 wherein the modeling applicationincludes the Weather Research and Forecasting Model.
 12. The system ofclaim 7 wherein the processor is further configured to encrypt the oneor more components for transmission to the irrigation system; andwherein the irrigation system is further configured to decrypt the oneor more components received from the processor.
 13. The system of claim7 wherein the irrigation area does not have sufficient measuringapparatus to capture local information that is needed to calculate theone or more components that are to be used to compute the ET value forthe irrigation area.
 14. A system for providing irrigation control,comprising: a plurality of non-local data sources for providing data; aprocessor configured to receive data from one or more of the pluralityof non-local data sources and calculate weather parameters using amodeling application, the processor further configured to use theweather parameters to compute an evapotranspiration (ET) value for anirrigation area that is non-local with respect to the plurality ofnon-local data sources; and an irrigation system configured to receivethe ET value from the processor and provide appropriate irrigationcontrol for the irrigation area using the ET value.
 15. The system ofclaim 14 wherein the modeling application includes a mesoscale modelknown as MM5.
 16. The system of claim 14 wherein the modelingapplication includes and the Weather Research and Forecasting Model. 17.The system of claim 14 wherein the processor is further configured toencrypt the ET value for transmission to the irrigation system; andwherein the irrigation system is further configured to decrypt the ETvalue received from the processor.
 18. The system of claim 14 whereinthe irrigation area does not have sufficient measuring apparatus tocapture local information that is needed to calculate the ET value forthe irrigation area.
 19. A system for providing irrigation control,comprising: a plurality of non-local data sources for providing data; aprocessor configured to receive data from one or more of the pluralityof non-local data sources and calculate an evapotranspiration (ET) valuefor an irrigation area that is non-local with respect to the pluralityof non-local data sources, the processor further configured to decomposethe ET value into one or more components; and an irrigation systemconfigured to receive the one or more components from the processor. 20.The system of claim 19 wherein the irrigation system is furtherconfigured to use the one or more components received from the processorto derive the ET value and provide appropriate irrigation control forthe irrigation area based on the ET value computed by the processor. 21.The system of claim 19 wherein the processor is further configured touse a modeling application to calculate weather parameters using datareceived from one or more of the plurality of non-local data sources andfurther utilize the weather parameters to generate the one or morecomponents.
 22. The system of claim 21 wherein the modeling applicationincludes a mesoscale model known as MM5.
 23. The system of claim 21wherein the modeling application includes the Weather Research andForecasting Model.
 24. The system of claim 19 wherein the processor isfurther configured to encrypt the one or more components fortransmission to the irrigation system; and wherein the irrigation systemis further configured to decrypt the one or more components receivedfrom the processor.
 25. The system of claim 19 wherein the irrigationarea does not have sufficient measuring apparatus to capture localinformation that is needed to calculate the one or more components thatare to be used to compute the ET value for the irrigation area.
 26. Amethod for providing irrigation control, comprising: receiving data fromone or more non-local data sources; calculating an evapotranspiration(ET) value based on the data received from the one or more non-localdata sources, wherein the ET value is for an irrigation area that isnon-local with respect to the non-local data sources; and providingappropriate irrigation control for the irrigation area using the ETvalue.
 27. The method of claim 26 wherein calculating the ET valuefurther comprises: using a modeling application to calculate weatherparameters based on the data received from the one or more of theplurality of non-local data sources; and using the weather parameters tocalculate the ET value.
 28. The method of claim 27 wherein the modelingapplication includes a mesoscale model known as MM5.
 29. The method ofclaim 27 wherein the modeling application includes the Weather Researchand Forecasting Model.
 30. The method of claim 26 wherein an irrigationsystem is configured to provide the appropriate irrigation control, themethod further comprising: encrypting the ET value for transmission tothe irrigation system; decrypting the ET value; and using the decryptedET value to provide the appropriate irrigation control.
 31. The methodof claim 26 wherein the irrigation area does not have sufficientmeasuring apparatus to capture local information that is needed tocalculate the ET value for the irrigation area.
 32. A method forproviding irrigation control, comprising: receiving data from one ormore non-local data sources; calculating one or more components to beused for computing an evapotranspiration (ET) value based on the datareceived from the one or more non-local data sources, wherein the ETvalue is for an irrigation area that is non-local with respect to thenon-local data sources; and transmitting the one or more components toan irrigation system.
 33. The method of claim 32 further comprising:receiving the one or more components at the irrigation system; computingthe ET value at the irrigation system using the one or more components;and providing appropriate irrigation control based on the computed ETvalue.
 34. The method of claim 32 wherein calculating the one or morecomponents further comprises: using a modeling application to calculateweather parameters based on the data received from one or more of theplurality of non-local data sources; and using the weather parameters togenerate the one or more components.
 35. The method of claim 34 whereinthe modeling application includes a mesoscale model known as MM5. 36.The method of claim 34 wherein the modeling application includes theWeather Research and Forecasting Model.
 37. The method of claim 32further comprising: encrypting the one or more components fortransmission to the irrigation system; and decrypting the one or morecomponents at the irrigation system.
 38. The method of claim 32 whereinthe irrigation area does not have sufficient measuring apparatus tocapture local information that is needed to calculate the one or morecomponents that are to be used to compute the ET value for theirrigation area.
 39. A method for providing irrigation control,comprising: receiving data from one or more non-local data sources;calculating weather parameters using a modeling application based on thedata received from the one or more non-local data sources; using theweather parameters to compute an evapotranspiration (ET) value for anirrigation area that is non-local with respect to the non-local datasources; and transmitting the ET value to an irrigation system.
 40. Themethod of claim 39 further comprising: directing the irrigation systemto provide appropriate irrigation control for the irrigation area basedon the ET value.
 41. The method of claim 39 wherein the modelingapplication includes a mesoscale model known as MM5.
 42. The method ofclaim 39 wherein the modeling application includes the Weather Researchand Forecasting Model.
 43. The method of claim 39 further comprising:encrypting the ET value for transmission to the irrigation system; anddecrypting the ET value at the irrigation system.
 44. The method ofclaim 39 wherein the irrigation area does not have sufficient measuringapparatus to capture local information that is needed to calculate theET value for the irrigation area.